Current sensor that detects a magnetic field produced by a current

Abstract

A current sensor includes a primary conductor in which a current flows, a magnetic sensor that detects a strength of a magnetic field produced by the current, and a magnetic body that surrounds a periphery of the primary conductor and the magnetic sensor. Output characteristics of the magnetic sensor include a low-output region in which a measured voltage value lower than a virtual output voltage proportional to a value of the current is outputted. Magnetization characteristics of the magnetic body include a magnetic saturation region in which permeability decreases in ranges where an absolute value of the current is no less than a threshold. An output of the magnetic sensor is corrected such that the measured voltage value increases as a result of a magnetic field leaking from the magnetic body that is within the magnetic saturation region acting on the magnetic sensor that is in the low-output region.

What is claimed is: 
     
       1. A current sensor comprising:
 a primary conductor in which a current to be measured flows; 
 at least one magnetic sensor that detects a strength of a magnetic field produced by the current flowing in the primary conductor; and 
 a magnetic body that surrounds peripheries of the primary conductor and the magnetic sensor; wherein 
 output characteristics of the magnetic sensor include a low-output region in which a measured voltage value lower than a virtual output voltage proportional to a value of the current is outputted; 
 magnetization characteristics of the magnetic body include a magnetic saturation region in which permeability decreases in ranges where an absolute value of the current is no less than a threshold; and 
 an output of the magnetic sensor is corrected such that the measured voltage value increases as a result of a magnetic field leaking from the magnetic body that is within the magnetic saturation region acting on the magnetic sensor that is in the low-output region. 
 
     
     
       2. The current sensor according to  claim 1 , wherein
 the primary conductor has a plate shape; and 
 the magnetic sensor is capable of detecting a magnetic field in a direction perpendicular or substantially perpendicular to both a thickness direction of the primary conductor and a direction in which the current flows. 
 
     
     
       3. The current sensor according to  claim 1 , wherein the magnetic sensor is disposed on at least one of one side and another side of the primary conductor in the thickness direction of the primary conductor, in a central area of the primary conductor in the width direction of the primary conductor. 
     
     
       4. The current sensor according to  claim 1 , wherein
 a first magnetic sensor and a second magnetic sensor are included in the magnetic sensor; and 
 the first magnetic sensor and the second magnetic sensor are positioned opposite to each other with the primary conductor interposed therebetween. 
 
     
     
       5. The current sensor according to  claim 4 , further comprising:
 a calculator that calculates the value of the current by processing a detection value of the first magnetic sensor and a detection value of the second magnetic sensor; wherein 
 the detection value of the first magnetic sensor and the detection value of the second magnetic sensor have opposite phases with respect to the strength of the magnetic field produced by the current flowing in the primary conductor; and 
 the calculator is a subtractor or a differential amplifier. 
 
     
     
       6. The current sensor according to  claim 4 , further comprising:
 a calculator that calculates the value of the current by processing a detection value of the first magnetic sensor and a detection value of the second magnetic sensor; wherein 
 the detection value of the first magnetic sensor and the detection value of the second magnetic sensor have the same phase with respect to the strength of the magnetic field produced by the current flowing in the primary conductor; and 
 the calculator is an adder or a summing amplifier. 
 
     
     
       7. A current sensor comprising:
 a primary conductor in which a current to be measured flows; 
 at least one magnetic sensor that detects a strength of a magnetic field produced by the current flowing in the primary conductor; and 
 a magnetic body that surrounds peripheries of the primary conductor and the magnetic sensor; wherein 
 the magnetic body includes a plate that extends along a direction of a detection axis of the magnetic sensor, and opposes the magnetic sensor at a distance from the magnetic sensor; and 
 an output voltage of the magnetic sensor is corrected to approach a virtual output voltage proportional to a value of the current as a result of a magnetic field leaking from the plate magnetically saturated by a magnetic field produced by the current acting on the magnetic sensor. 
 
     
     
       8. The current sensor according to  claim 7 , wherein
 the magnetic body includes a first magnetic body including the plate and a second magnetic body positioned at a distance from the first magnetic body; and 
 the first magnetic body is magnetically saturated by the magnetic field produced by the current before the second magnetic body. 
 
     
     
       9. The current sensor according to  claim 8 , wherein
 a gap is provided in the second magnetic body and causes the second magnetic body to be shaped as a tube that is non-continuous in a circumferential direction. 
 
     
     
       10. The current sensor according to  claim 9 , wherein the second magnetic body surrounds a periphery of the first magnetic body. 
     
     
       11. The current sensor according to  claim 9 , wherein the first magnetic body is positioned at the gap of the second magnetic body. 
     
     
       12. The current sensor according to  claim 8 , wherein the second magnetic body is shaped as a tube that is continuous throughout the entire circumference. 
     
     
       13. The current sensor according to  claim 8 , wherein
 the first magnetic body includes at least one first magnetic body member; and 
 the second magnetic body includes at least one second magnetic body member. 
 
     
     
       14. The current sensor according to  claim 13 , wherein the first magnetic body member has a plate shape. 
     
     
       15. The current sensor according to  claim 13 , wherein
 the first magnetic body includes the two first magnetic body members; and 
 the magnetic sensor is positioned between the two first magnetic body members. 
 
     
     
       16. The current sensor according to  claim 7 , wherein
 the primary conductor has a plate shape; and 
 the magnetic sensor is capable of detecting a magnetic field in a direction perpendicular or substantially perpendicular to both a thickness direction of the primary conductor and a direction in which the current flows. 
 
     
     
       17. The current sensor according to  claim 7 , wherein the magnetic sensor is disposed on at least one of one side and another side of the primary conductor in the thickness direction of the primary conductor, in a central area of the primary conductor in the width direction of the primary conductor. 
     
     
       18. The current sensor according to  claim 7 , wherein
 a first magnetic sensor and a second magnetic sensor are included in the magnetic sensor; and 
 the first magnetic sensor and the second magnetic sensor are positioned opposite to each other with the primary conductor interposed therebetween. 
 
     
     
       19. The current sensor according to  claim 18 , further comprising:
 a calculator that calculates the value of the current by processing a detection value of the first magnetic sensor and a detection value of the second magnetic sensor; wherein 
 the detection value of the first magnetic sensor and the detection value of the second magnetic sensor have opposite phases with respect to the strength of the magnetic field produced by the current flowing in the primary conductor; and 
 the calculator is a subtractor or a differential amplifier. 
 
     
     
       20. The current sensor according to  claim 18 , further comprising:
 a calculator that calculates the value of the current by processing a detection value of the first magnetic sensor and a detection value of the second magnetic sensor; wherein 
 the detection value of the first magnetic sensor and the detection value of the second magnetic sensor have the same phase with respect to the strength of the magnetic field produced by the current flowing in the primary conductor; and 
 the calculator is an adder or a summing amplifier.